Timeskip, but only a short one.

You had just finished helping your mom move all the boxes in. You unpacked the necessary things, but most of the stuff from your old house stayed concealed inside of poorly labeled boxes. Both of you are clearly exhausted.

"Okay. Lets call it!" Your mother says clapping her hands together. "I'll catch a shower upstairs, you can take one down here. Then I'm heading to bed."

"Okay."

You glanced up at your mom as she walked up the stairs. Her ass had caught your attention. It's never done that before. Maybe it was because you were tired after all the work, but none of that mattered. What did matter though, was that you couldn't help but stare at her ass the whole time she went up the stairs. After that you took a while to search for the downstairs bathroom, when you finally found it a wicked idea crossed your mind.